Every particle has an antiparticle. An antiparticle is identical to its corresponding particle in mass , but it has opposite charges. For example, the electron with an electric charge of -1 has an anti-electron, also called positron with the electric charge of +1. If all the charges of a particle equal 0, there is no way to tell the difference between the particle and its antiparticle. In this case we say, the particle is its own antiparticle.

When a particle meets its corresponding antiparticle, they annihilate .

Read about antiparticles on the main page.

http://info.web.cern.ch/info/Announcements/CERN/2000/0808-ADStartUp/Story/Story-en.html#9

About Antiparticle in German. (Antiteilchen)